Coexistence of Radio Altimeters and 5G Networks: Modeling, Analysis, and Design

Radio altimeter (RA) accuracy is crucial to aircraft safety in critical scenarios such as low visibility, close proximity to terrain, collision avoidance, and autoland (automatic landing) procedures. Nowadays, there is growing concern that possibly damaging interference from 5G communications systems in C-band may interfere with the operation of RA at 4.2 - 4.4 GHz. Some countries and international organisations have already taken corrective measures. In this work, we study a system where radio altimeter and 5G network exist in the same area. the system is composed of one airplane landing in a straight direction parallel to the runway and 5G base stations (5G-BSs) deployed on the ground. Our ultimate goal is to analyse the interference caused by 5G-BSs and ensure a safe operation environment for the radio altimeter. Using tools from stochastic geometry, we determine the CDF of the interference caused by the 5G-BSs. We use the probability of having an interference greater then a specific threshold as a metric. We want this metric to be as close as possible to zero. Thus, we propose different exclusion zones as a solution to mitigate interference. Then, we analyse the performance of the 5G network to evaluate the impact of deploying exclusion zones on it. We verify our findings using Monte-Carlo simulations and draw multiple useful insights.